This invention relates generally to trocar systems including cannulas and, more specifically, to trocars having a balloon retention device.
Trocar systems have been of particular advantage in facilitating less invasive surgery across a body wall and within a body cavity. This is particularly true in abdominal surgery where trocars have provided a working channel across the abdominal wall to facilitate the use of instruments within the abdominal cavity.
Trocar systems typically include a cannula, which provides the working channel, and an obturator that is used to place the cannula across a body wall, such as the abdominal wall. The obturator is inserted into the working channel of the cannula and pushed through the body wall with a penetration force of sufficient magnitude to result in penetration of the body wall. Alternatively, the cannula with an obturator is passed through an incision formed by the “Hassan,” or cut-down, technique, which includes incremental incisions through the body wall until the body wall is incised through its entire thickness. Once the cannula has traversed the body wall, the obturator can be removed.
With the cannula in place in the body wall, various instruments may be inserted through the cannula into the body cavity. One or more cannulas may be used during a procedure. During the procedure, the surgeon manipulates the instruments in the cannulas, sometimes using more than one instrument at a time. The manipulation of an instrument by a surgeon may cause frictional forces between the instrument and the cannula in which the instrument is inserted. These frictional forces may result in movement of the cannula in an inward or outward direction within the body wall. If the cannula is not fixed in place, the proximal or distal motions of the instruments through the cannula may potentially cause the cannula to slip out of the body wall or to protrude further into the body cavity, possibly leading to injury to the patient.
The surfaces of the cannula associated with a trocar are generally smooth. The smoothness of a cannula surface makes placement of the cannula through a body wall relatively easy and safe. However, a smooth cannula may not have the desired retention characteristics once the cannula has been placed through a body wall. This may present problems as instruments and specimens are removed from a body cavity through the cannula and the associated seal systems of the trocar. It is highly desirable for a cannula to remain fixed in the most appropriate position once placed. Additionally, if the Hassan technique is used, the incision may be larger than the cannula that may be placed through the incision. Therefore, it is necessary to provide a means to seal the incision site after the cannula has been inserted in order to insufflate a patient.
Many solutions to the issue of trocar-cannula fixation or stabilization have been formed. These solutions include an inflatable balloon attached to the distal portion of the cannula with a thick foam bolster proximal to the insertion point into the body wall, raised threads or raised rings associated with the outer surface of the cannula, mechanically deployable enlarging portions arranged at the distal end of a cannula and suture loops or hooks associated with the proximal end of the trocar. These solutions have provided some degree of fixation or stabilization, but they have often led to cannulas having a larger outside diameter. Further, the thick foam bolster associated with balloon trocars has reduced the usable length of the cannula. There remains a need for a cannula fixation or stabilization device that includes a sleeve having attachment means that minimize the increase in diameter. Additionally, the cannula fixation or stabilization device may include a lower profile and increase the working length of the cannula.